Ionizable organic chemicals (IOCs) such as organic acids and bases are an important substance class requiring aquatic hazard evaluation. Although the aquatic toxicity of IOCs is highly dependent on the water pH, many toxicity studies in the literature cannot be interpreted because pH was not reported or not kept constant during the experiment, calling for an adaptation and improvement of testing guidelines. The modulating influence of pH on toxicity is mainly caused by pH-dependent uptake and bioaccumulatio n of IOCs, which can be described by ion-trapping and toxicokinetic models. The internal effect concentrations of IOCs were found to be independent of the external pH because of organisms' and cells' ability to maintain a stable internal pH milieu. If the external pH is close to the internal pH, existing quantitative structure - activity relationships (QSARs) for neutral organics can be adapted by substituting the octanol -water partition coefficient by the ionization- corrected liposome - water distribution ratio as the hydrophobicity descriptor, demonstrated by modification of the target lipid model. Charged, zwitterionic and neutral species of an IOC can all contribute to observed toxicity, either through concentration-additive mixture effects or by interaction of different species, as is the case for uncoupling of mitochondrial respiration. For specifically acting IOCs, we recommend a 2-step screening procedure with ion-trapping/QSAR models used to predict the baseline toxicity, followed by adjustment using the toxic ratio derived from in vitro systems. Receptor- or plasma-binding models also show promise for elucidating IOC toxicity. The present review is intended to help demystify the ecotoxicity of IOCs and provide recommendations for their hazard and risk assessment.

Escher, B.I., Stapleton, H.M., Schymanski, E.L., 2020. Tracking complex mixtures of chemicals in our changing environment. Science 367, 388-392.

http://science.sciencemag.org/content/367/6476/388.abstract Chemicals have improved our quality of life, but the resulting environmental pollution has the potential to cause detrimental effects on humans and the environment. People and biota are chronically exposed to thousands of chemicals from various environmental sources through multiple pathways. Environmental chemists and toxicologists have moved beyond detecting and quantifying single chemicals to characterizing complex mixtures of chemicals in indoor and outdoor environments and biological matrices. We highlight analytical and bioanalytical approaches to isolating, characterizing, and tracking groups of chemicals of concern in complex matrices. Techniques that combine chemical analysis and bioassays have the potential to facilitate the identification of mixtures of chemicals that pose a combined risk.

Fakher, S., Imqam, A., 2020. Application of carbon dioxide injection in shale oil reservoirs for increasing oil recovery and carbon dioxide storage. Fuel 265, 116944.

http://www.sciencedirect.com/science/article/pii/S0016236119323373 Carbon dioxide (CO ) injection is an enhanced oil recovery method that has the potential to increase oil 2 recovery from unconventional shale reservoirs while also storing a portion of the injected CO into the reservoir 2 thus reducing the CO environmental impact. This research studies the ability of cyclic CO injection to increase 2 2 oil recovery from shale cores and the impact of different factors on the oil recovery potential. The research then studies the ability to store the injected CO in the shale through adsorption and the storage capacity at different 2 reservoir thermodynamic conditions. Oil recovery was impacted significantly by the CO injection pressure. 2 The CO phase was also found to be a factor related to the CO injection pressure and also had a strong impact 2 2 on oil recovery. Increasing the soaking time of the CO increased the oil recovery due to the increase in the 2 interaction time between the CO and the crude oil. The storage potential of the CO in the shale was influenced 2 2 significantly by the pressure and temperature. Increasing the CO injection pressure increased the CO 2 2 adsorption, while increasing the temperature decreased the adsorption capacity. Based on the experiments conducted, it was found that cyclic CO injection could be a means of both increasing oil recovery from shale 2 reservoirs and also for CO storage operations to reduce CO environmental impact. 2 2

Fan, J.-x., Shen, S.-z., Erwin, D.H., Sadler, P.M., MacLeod, N., Cheng, Q.-m., Hou, X.-d., Yang, J., Wang, X.-d., Wang, Y., Zhang, H., Chen, X., Li, G.-x., Zhang, Y.-c., Shi, Y.-k., Yuan, D.-x., Chen, Q., Zhang, L.-n., Li, C.,